add v1.60.3 release note

Author: c9s

doc/release/v1.60.3.md

@@ -0,0 +1,4 @@
+[Full Changelog](https://github.com/c9s/bbgo/compare/v1.60.2...main)
+
+ - FIX: fix xmaker default price
+ - [#1744](https://github.com/c9s/bbgo/pull/1744): call b.EmitNew() when new order is added into activeorderbook